[Boatanchors] OT: Zenith Royal 7000 overhaul in progress. . .

[Phil]

Yeah, it's only what I call a "Baby Boatanchor" but I thought some of 
you might be interested inb the post I just made to the "TransOceanic 
Fanatic" group.

*************************************

Hi All,

Awhile back I mentioned that a friend sent me a Zenith Royal 7000 
TransOceanic to overhaul and align for him.  I've done a couple of these 
for him in years past and he has several more to do.  He really likes 
them :)

First, let me say that over the years I've done a number of these sets 
(specifically the Royal 7000), so am pretty experienced on them!  Having 
been "radioactive" for over 60 years (cut my teeth on tubes and still 
like them), I've developed some 'procedures' (gee, sounds like a 
Doctor's Visit) that I tend to follow in working on **any** set.

EVERY set has it's own unique personality, even sets of the same model.  
NEARLY all the Royal 7000's that I've worked on have been fairly 
routine, that is, they played but had the usual dirty controls, 
alignment problems etc, but few REALLY tough problems.

This animal was a horse of a different color.  It seemed to fight me at 
EVERY turn.  It's a good thing I do these more for the enjoyment (and a 
bit of spending money), because if I charged  an "hourly shop rate"  
this set would have been uneconomical to repair.  Especially since some 
of the chrome is less than spectacular, missing door booklet etc.

**************************************

STEP BY STEP DETAILS. . .

OK, here are the detailed step-by-step process this set went through.  
As I have to do nearly ALL work under a lit magnifier and find long 
hours at the bench (sitting on tall stool) hard on my legs and knees I 
tend to take "baby steps" now-a-days.

28 Apr 2016: Arrived, checked, no power cord or Front Door Booklet included.
Bench Check.  Plays on FM, NO AM, LW, SW or BFO.

29 Apr 2016: Suspect a bad AM Front end transistor, subbed all 
transistors, no joy.

Inject 455kHz from Signal generator into IF strip, no output. Check 
Voltages, all IF strip Voltages VERY low.  Check Voltage Regulator 
Transistor Voltages. When touching 1 pin receiver comes to life.  Remove 
Transistor, tighten/clean socket contacts, AM is now good.  
Cleaned/tightened all transistor socket contacts.

Sprayed noisy bandswitch & controls with DeOxit.  After cleaning, blew 
out the excess. (One of the first things I do to give the switch time to 
drain/dry before later final alignment).

4 May 2016:  Replaced 8 Electrolytic Capacitors.  Secured slipping dial 
pointer to the dial cord.  Audio output MUCH lower than expected.

6 May 2016:  Located & repaired low volume problem. Problem was two 
adjacent wires in AF section touching.  Suspect wires were nearly 
shorted from the factory and movement of replacing parts did the evil 
deed. Reworking that section hidden behind the controls entails some 
extensive parts movement and things are TIGHT in there.

   Check operation on all functions and bands. BFO still not working 
(didn't work at initial checkout).

7 May 2016:  Troubleshoot BFO, substitute transistor, check Voltage on 
BFO switch output, ~5.7VDC as it should be.  FINALLY I take a tuning 
tool and adjust the BFO coil, several turns in and I have BFO.  NOTE:  
The LAST thing I do when troubleshooting a problem is to start adjusting 
coils/trimmer caps as they're rarely off much UNLESS somebody has been 
in the set with a "Golden Screwdriver".

It appears set is now fully functional and I'll do a complete alignment 
and final burn-in the first of the week.  I'll run it most of the 
weekend to make SURE that nothing else dies an early death.

**************************************

FINAL NOTES about Capacitors.

1.  There are still a couple 'lytic capacitors that DIDN'T get 
replaced.  I didn't feel that the risks involved in getting to them were 
worth it.

2.  I DID test ALL removed capacitorsafter removing them.  First for 
value on the digital LCR meter, THEN for ESR on the digital ESR meter.  
ALL tested well within spec, the ESR results especially surprised me!  
It made me feel a bit better about NOT replacing the ones that were VERY 
difficult to get to.


-- 
73 From "The Beaconeer's Lair"
Phil, KO6BB
http://www.qsl.net/ko6bb/  (Web Page)

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